General purposes microprocessors typically include or support various security and protection mechanisms. Virtual memory support, for example, enables multitask execution environments by maintaining distinct physical memory locations for different applications so that application programmers can define and refer to a location in memory without fear that a different application will have access to that same memory location. Microprocessors may also support the use of protection rings to implement various degrees of access restriction security for core operating system routines. If, however, a rogue application defeats the hierarchical protection mechanism implemented by the operating system, a reliable secondary mechanism to provide supplemental security would be beneficial.